Advanced technology frame structure with backward compatibility

ABSTRACT

An advanced technology frame structure is described herein. The advanced technology frame structure can enhance a first technology frame structure in dimensions of time, frequency, or a combination of time and frequency. A second technology frame structure time division multiplexes second technology subframes with the first technology downlink and uplink subframes. The first technology downlink subframe can be divided into a first technology downlink subframe and one or more second technology downlink subframes. Similarly, the first technology uplink subframe can be divided into a first uplink subframe and one or more second technology uplink subframes. These principles can be expanded upon and can be applied in many communication systems.

CROSS-REFERENCES TO RELATED APPLICATIONS

The application claims the benefit of U.S. Provisional PatentApplication No. 60/986,257 filed Nov. 7, 2007 for “802.16m FRAMESTRUCTURE TO ENABLE LEGACY SUPPORT, TECHNOLOGY EVOLUTION, AND REDUCEDLATENCY”; and U.S. Provisional Patent Application No. 61/030,183 filedFeb. 20, 2008 for “ADVANCED TECHNOLOGY FRAME STRUCTURE WITH BACKWARDCOMPATIBILITY”; which are all incorporated herein by reference in theirentirety for all purposes.

BACKGROUND

I. Field of the Invention

The invention relates to the field of wireless communications. Moreparticularly, the invention relates to an advanced technology framestructure.

II. Related Art

It is a constant challenge for communication systems to integratetechnological improvements in order to remain competitive with laterdeveloped communication systems implementing more advanced technology.The problem is even more apparent in wireless communication systems thathave large investments in previously installed infrastructure.

A communication system risks becoming obsolete if it does notincorporate system improvements. However, the implementation of newtechnology into a communication system typically accommodates legacydevices. One way of supporting legacy devices is to develop a parallelinfrastructure for supporting the new technology while slowly phasingout the legacy infrastructure. As can be imagined, supporting twoindependent systems is a costly approach to providing legacy support.Another approach is to implement updates that are backward compatiblewith legacy devices. However, often, the architecture of the legacydevices creates a bottleneck for system improvements.

There is a constant challenge to implement improvements into wirelesscommunication systems, while maintaining support for legacy devices.

BRIEF SUMMARY

An advanced technology frame structure with backward compatibility andassociated methods and systems are described herein. As a specificexample, the frame structure, methods and systems herein described canbe applied in a WiMax Orthogonal Frequency Division Multiple Access(OFDMA) communication system, although their use is not limited thereto.The advanced technology frame structure supports legacy devices withlittle or no change to and minimal effect on the legacy devices andenables the use of new physical layer and MAC layer enhancements thatare not supported by the legacy system. In one demonstrative embodiment,the advanced technology frame structure can enhance the existing framestructure in dimensions of time, frequency, or a combination of time andfrequency. In another demonstrative embodiment, the advanced technologyframe structure time division multiplexes advanced technology subframeswith the existing downlink and uplink subframes. For example, theexisting downlink subframe can be divided into a legacy downlinksubframe and an advanced technology downlink subframe. Similarly, theexisting uplink subframe can be divided into a legacy uplink subframeand an advanced technology uplink subframe.

Demonstrative embodiments of the disclosure include a first base stationtransmitter/receiver communicating a downlink subframe. The downlinksubframe starts at a first time and ends at a second time. The downlinksubframe includes a downlink legacy technology sub-subframe, a downlinkadvanced technology sub-subframe (ending at a third time) and an uplinkadvanced technology sub-subframe (beginning approximately at the thirdtime and ending on or before the second time.) A neighboring basestation transmitter transmits a limited second downlink subframe,starting at the first time and ending before or at the third time. Thelimited second downlink subframe includes only a legacy downlinktechnology sub-subframe. The neighboring base station refrains fromtransmitting or receiving at between the third time and the second time.In one demonstrative embodiment, the downlink legacy technologysub-subframe ends at approximately a fourth time and the downlinkadvanced technology sub-subframe begins at approximately the fourth timeand the first base station transmitter/receiver adjusts the occurrenceof the fourth time on a frame to frame basis. In one aspect the firstbase station transmitter/receiver further communicates an uplinksubframe. The uplink subframe begins at approximately the second timeand ends at a fifth time. The uplink subframe includes an seconddownlink advanced technology sub-subframe beginning at approximately thesecond time, as well as an uplink legacy technology sub-subframe and asecond uplink advanced technology sub-subframe having a boundarytherebetween at a sixth time, wherein the sixth time is between thesecond time and the fifth time. The neighboring base stationtransmitter/receiver may receive a limited uplink sub-subframe beginningat approximately the end of the second downlink advanced technologysub-subframe. The first base station transmitter/receiver may adjust theoccurrence of the sixth time on a frame to frame basis.

Further demonstrative embodiments of the disclosure include a first basestation receiving a first uplink communication from a client stationoperating according to a first technology format. The first uplinkcommunication is received between a first time and a second time. Thefirst base station also receives a second uplink communication from asecond client station after the second time and before a third time. Thesecond client station operates in accordance with a second technologyformat. A neighboring base station receives between the first time andthe second time and between the second time and the third time. Itreceives a plurality of uplink communications from a plurality of clientstations operating according to the first technology format.

Yet further demonstrative embodiments of the disclosure include a firstbase station transmitter that transmits a downlink subframe beginning ata first time and ending at a second time. The downlink subframe beginswith a downlink legacy technology sub-subframe and ends with an uplinkadvanced technology sub-subframe. The uplink advanced technologysub-subframe begins at a third time. A neighboring base station receivesa limited uplink subframe starting at the third time and ending at thesecond time. The neighboring base station may transmit over a limiteddownlink subframe beginning at approximately the second time.

Further demonstrative embodiments of the disclosure include a subframeportion of a legacy communication system that time division multiplexesa legacy sub-subframe into an advanced technology sub-subframe. Aportion of the subframe portion to allocate to supporting advancedtechnology communications is determined. The process of time divisionmultiplexing the subframe portion may comprise dynamically allocating aduration of the legacy sub-subframe based on the portion of the subframeportion to allocate to supporting advanced technology communications.The process of time division multiplexing the subframe portion maycomprise time division multiplexing a downlink subframe portion of thelegacy communication system into a legacy downlink sub-subframe and anadvanced technology downlink sub-subframe. It may also comprise timedivision multiplexing an uplink subframe portion of the legacycommunication system into a legacy uplink sub-subframe and an advancedtechnology uplink sub-subframe. The duration of the downlink subframeportion may be fixed and a ratio of a duration of the legacy downlinksub-subframe to a duration of the advanced technology downlinksub-subframe may be dynamically variable. The process of time divisionmultiplexing the subframe portion may comprise time divisionmultiplexing a downlink subframe portion of the legacy communicationsystem into a legacy downlink sub-subframe and a first advancedtechnology downlink sub-subframe and a first advanced technology uplinksub-subframe. It may also comprise time division multiplexing an uplinksubframe portion of the legacy communication system into a legacy uplinksub-subframe and a second advanced technology downlink sub-subframe anda second advanced technology uplink sub-subframe. The second advancedtechnology downlink sub-subframe may occur prior to the legacy uplinksub-subframe.

Further demonstrative embodiments of the disclosure include the legacydownlink sub-subframe including an indication of an allocation withinthe first advanced technology downlink sub-subframe. In otherdemonstrative embodiments, the legacy downlink sub-subframe includes anindication of a downlink map within the first advanced technologydownlink sub-subframe. In yet another demonstrative embodiment, thefirst advanced technology downlink sub-subframe includes a preamble. Thesecond advanced technology downlink sub-subframe may occur at abeginning of the uplink subframe portion of the legacy communicationsystem. A beginning of an advanced technology frame having the timedivision multiplexed subframe portion may be synchronized with abeginning of a legacy frame. The time division multiplexed sub-subframesmay be expanded to cover additional frequency portions.

Further demonstrative embodiments of the disclosure include a basestation that supports legacy communications and advanced technologycommunications. The base station has several elements. It has ascheduler configured to determine the resources to allocate to advancedtechnology communications. It has a multiplexer configured to timedivision multiplex a subframe portion of a legacy communication systeminto a legacy sub-subframe and an advanced technology sub-subframe basedon a control from the scheduler. It has a legacy resource mapperconfigured to allocate legacy communications within the legacysub-subframe. And, it has an advanced technology resource mapperconfigured to allocate advanced technology communications within theadvanced technology sub-subframe. The scheduler may determine theresources allocated based on resource allocation requests for advancedtechnology communications, such as, for example, based on informationreceived from a system controller. The multiplexer may time divisionmultiplex a downlink subframe portion distinct from an uplink subframeportion.

Further demonstrative embodiments of the disclosure include a clientstation that supports advanced technology communications. It has areceiver configured to receive a time division multiplexed subframeportion of a legacy communication system having a legacy sub-subframeand an advanced technology sub-subframe. It has a legacy map decoderconfigured to access a resource map from the legacy sub-subframe anddetermine a resource allocation for an advanced technology map. And ithas an advanced technology map decoder configured to access the advancedtechnology map and determine an advanced technology resource allocationin the advanced technology sub-subframe.

Further demonstrative embodiments of the disclosure include a basestation that creates a subframe designated as a downlink portion of aframe according to a first technology format. A base station inserts anuplink sub-subframe according to an alternate technology into thedownlink subframe.

Further demonstrative embodiments of the disclosure include a clientstation that receives a frame header in a first technology format. It isparsed to determine an alternate technology format region. A resourcegrant message within the alternate technology format region is received.Alternate technology formatted data is either transmitted or receivedwithin the alternate technology format region according to the grantmessage.

Further demonstrative embodiments of the disclosure include a basestation that creates a frame header for a frame. The frame headerindicates a portion of the frame including an alternate technologyregion. The base station populates a first region of the frame with datain a first technology format. The base station populates the alternatetechnology region with data in an alternate technology format. Theresulting frame is transmitted.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of embodiments of the disclosurewill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings, in which like elements bearlike reference numerals.

FIGS. 1 a-b are simplified timing diagrams of a legacy frame structureand an embodiment of an advanced technology frame structure.

FIG. 2 is a simplified timing diagram of a detailed view of anembodiment of an advanced technology frame structure.

FIGS. 3 a-b are simplified timing diagrams of embodiments of advancedtechnology frame structures.

FIG. 4 is a simplified timing diagram of time synchronization betweenembodiments of advanced technology frame structures.

FIG. 5 is a simplified timing diagram of time synchronization betweenembodiments of advanced technology frame structures.

FIGS. 6 a-d are simplified timing diagrams of embodiments of an advancedtechnology frame structure as seen from different device perspectives.

FIGS. 7 a-c are simplified timing diagrams of embodiments of an advancedtechnology frame structure having further expansion along the frequencydimension.

FIG. 8 is a simplified functional block diagram of a system implementingan advanced technology frame structure.

FIG. 9 is a simplified functional block diagram of an embodiment of abase station implementing an advanced technology frame structure.

FIG. 10 is a simplified functional block diagram of an embodiment of aclient station supporting advanced technology frame structure.

FIG. 11 is a flow chart illustrating an advanced technology framestructure incorporating several features.

FIG. 12 is a flow chart illustrating a process for creating anintegrated, backwards compatible advanced technology frame structure.

FIG. 13 is a flow chart illustrating a process for receiving anintegrated, backwards compatible advanced frame structure at a clientstation.

FIG. 14 is a flow chart illustrating a process for creating anintegrated, backwards compatible advanced frame structure fortransmission over a wireless link.

FIG. 15 is a flow chart illustrating a process for using a system thatincludes both advanced mode enabled base station transmitters and legacyonly base station transmitters.

FIG. 16 is a flow chart illustrating a process for using a system thatincludes both advanced mode enabled base stations and legacy only basestations.

DETAILED DESCRIPTION OF THE INVENTION

An advanced technology frame structure with backward compatibility,methods for implementing the advanced technology frame structure, andapparatus for implementing and communicating using the advancedtechnology frame structure are described herein. The advanced technologyframe structure supports legacy communications as well as advancedtechnology communications by time division multiplexing a legacy framestructure such that minimal or reasonable changes are required forsupporting both communications.

The frame structure and apparatus described herein use improvements tolegacy IEEE 802.16e Orthogonal Frequency Division Multiple Access(OFDMA) time division duplex (TDD) frame structure as an example.However, the method and embodiments described herein are not generallylimited to application in an OFDMA system, nor are they limited toapplication in a TDD system. In the timing diagrams, the frame structureincludes a time dimension and a frequency dimension. The time dimensionis illustrated on the horizontal axis and the frequency dimension isillustrated on the vertical axis. The principles describe herein can beapplied to other system such as other IEEE 802.16-type systems, WiBro,Wi-Fi, Long Term Evolution (LTE) and proprietary systems. In one aspect,the advanced technology frame structure supports legacy devices withlittle or no change to and minimal effect on the legacy devices andenables the use of new physical layer and MAC layer enhancements thatare not supported by the legacy system.

In the description that follows, we often refer to a legacy and advancedtechnology backwards compatible frame. However, in general, thetechniques described herein can be used to provide combined operation ofa first technology format and one or more additional technology formats.The “legacy” system need not have been developed or deployed before the“advanced” system.

The first and second technology formats may typically have some featuresin common. They may differ by employing different overhead messaging,physically layer techniques, encoding techniques, access techniques,power control, physical (PHY) layer parameters, media access (MAC) layerparameters and the like.

FIGS. 1 a and 1 b are simplified timing diagrams of a legacy framestructure 102 and an embodiment of an integrated advanced technologyframe structure with backwards compatibility 110. The legacy framestructure 102 is configured as a TDD frame having a legacy downlinksubframe portion 104 followed by a legacy uplink subframe portion 106.The duration of the legacy frame 102 is fixed, although the duration ofeach subframe portion 104, 106 may vary across distinct frames. That is,each of the subframe portions 104, 106 may occupy varied percentages ofthe entire frame duration across distinct frames, but the sum of thedownlink subframe duration and the uplink subframe duration is constant.In some systems, the ratio of the subframe portions is set on a systemwide basis.

An embodiment of an advanced technology frame structure 110 that isbackward compatible with the legacy frame structure 102 is shown in FIG.1 b. For the purposes of discussion, the downlink subframe 112 anduplink subframe 114 in the advanced technology frame are shown as havingthe same duration as the downlink subframe 104 and uplink subframe 106in the legacy frame, although other variations can be implemented inoperation.

As shown in FIG. 1 b, the advanced technology frame 110 fully supportsthe legacy communications by retaining the legacy downlink sub-subframeportion 116 in its downlink subframe 112 and the legacy uplinksub-subframe portion 130 in its uplink subframe 114. Specifically, inthe advanced technology frame 110, the legacy downlink subframe portion112 is time division multiplexed into a legacy downlink sub-subframe 116and an advanced technology downlink sub-subframe 118. Similarly, thelegacy uplink subframe portion 114 is time division multiplexed into alegacy uplink sub-subframe 130 and an advanced technology uplinksub-subframe 132.

The portion of each sub-subframe that is allocated to legacycommunications or advanced technology communications can be fixed orvariable. In one embodiment, the ratio of a duration of the legacydownlink sub-subframe to a duration of the advanced technology downlinksub-subframe is dynamically variable, and can be based on, for example,resource allocation requests for each type of communications,predetermined ratios, client station capabilities, ratios of clientstation capabilities, and the like or some combination thereof.Similarly, the ratio between the duration of the legacy uplinksub-subframe and the duration of the advanced technology uplinksub-subframe is dynamically variable based upon one or more factors asnumerated above. Additionally, the respective ratios of legacy toadvanced technology durations can be different in the downlink anduplink subframe portions.

The legacy downlink sub-subframe 116 includes a header 120. Typically,the header 120 includes a preamble 122 which is used by the clientstation to acquire both time and frequency synchronization among otherinformation. In the embodiment shown in FIG. 1 b, the header 120indicates to the advanced mode client stations the location of anadvanced technology resource map etc. 124 within the advanced modedownlink subframe 118. Thus, in one embodiment, a client stationoperating in a system using the integrated advanced TDD frame structure110 shown in FIG. 1 b tracks the preamble 122 and retrieves informationfrom the header 120 or other element of the legacy mode downlinksub-subframe 116 regarding the location of the advanced technologyresource map etc. 124. The advanced mode map etc. 124 indicates resourceallocations within the advanced mode sub-subframe 118. In addition, inone embodiment, the advanced technology resource map etc. 124 alsoindicates resource allocations within the advanced mode sub-subframe132.

As shown in FIG. 1, the downlink advanced technology sub-subframe 118may include the advanced technology resource map etc. 124 that indicatesthe advanced technology downlink and uplink resource allocations grantedto the advanced technology enabled devices. The location of the advancedtechnology resource map etc. 124 is indicated in a downlink legacyresource map or an extension of a legacy resource map. Thus, in oneembodiment, a client station operating in a system using the integrated,backwards compatible advanced frame structure 110 as shown in FIG. 1tracks the preamble 122 and retrieves information from the header 102 orother element of the legacy mode downlink sub-subframe as to thelocation of the advanced technology resource map etc. 124.

FIG. 2 is a simplified timing diagram of a detailed view of anembodiment of an advanced technology frame structure 200 with backwardscompatibility. In FIG. 2, the advanced technology resource map etc. 124may be limited or omitted, and the advanced technology resourceallocation information can be communicated in an extension of the legacyresource map. For example, a legacy downlink resource map 208 within theheader 206 can include an extended identifier or code 210 thatidentifies an information element 220 that identifies the resourcesallocated to advanced technology communications, both uplink anddownlink. In another example, a legacy downlink resource map 208 caninclude a downlink advanced-mode granting information element. Thedownlink advanced-mode granting information element can grant thedownlink and uplink resource allocations in the advanced technologydownlink sub-subframe 204 and advanced mode technology uplinksub-subframe 222. The downlink advanced-mode pointer information element210 and the uplink advanced-mode extended identifier or grantinginformation element within the legacy uplink resource map 220 can bemade to be backward compatible to the legacy resource maps by usingextended codes or identifiers that have been reserved in the legacysystem for expansion.

An advanced mode client station operating in a system using thebackward-compatible advanced technology frame structure 200 acquiresboth time and frequency synchronization using the legacy preamble 212.In the embodiment shown in FIG. 2, downlink map information element 210within the header 206 indicates to the advanced mode client stations thelocation of allocations within the advanced mode downlink and uplinksub-subframes 204 and 222. Thus, in one embodiment, a client stationoperating in a system using the backwards compatible advanced framestructure 200 as shown in FIG. 2 tracks the preamble 212 and retrievesinformation from the header 206 or other element of the legacy modedownlink sub-subframe 202, such as downlink burst 214, regarding uplinkand downlink allocations within the advanced mode downlink and uplinksub-subframes 204 and 222.

FIGS. 3 a and 3 b are simplified timing diagrams of embodiments ofadvanced technology frame structures 302 and 304. FIG. 3 a illustratesthe advanced technology frame structure 302 similar to the one describedin FIG. 1 b. FIG. 3 b illustrates an alternative advanced technologyframe structure 304 supporting low latency communications for clientstations operating in the advanced mode.

In the low latency advanced technology frame structure 304 as shown inFIG. 3 b, a frame of 5 ms length, for example, is divided into first andsecond subframes 310 and 312 of fixed duration (e.g., 2.5 ms eachsubframe). Each of the first and second subframes 310 and 312 is timedivision multiplexed into a legacy sub-subframe 320, 330 and at leastone advanced technology downlink sub-subframe 322, 332 and at least oneuplink sub-subframe 324, 334, respectfully. As shown in FIG. 3 b, thefirst subframe 310 comprises the legacy downlink sub-subframe 320, aswell as both an advanced technology downlink sub-subframe 322 andadvanced technology uplink sub-subframe 324, while the second subframe312 comprises the legacy uplink subframe 330, as well as at least oneadvanced technology downlink sub-subframe 332 and advanced technologyuplink sub-subframe 334. As shown, each subframe portion includes anadvanced technology uplink sub-subframe and an advanced technologydownlink sub-subframe.

The first subframe 310 is configured with a different time divisionmultiplex ordering than the second subframe 312. As such, the advancedmode downlink sub-subframe 332 can be configured to begin at a fixedoffset from the beginning of the legacy sub-subframe 320. In oneembodiment, the fixed offset is configured such that a downlinksub-subframes occurs periodically, such as at 2.5 ms intervals as shownin the exemplary embodiment of FIG. 3 b. In such a configuration, fromthe perspective of an advanced mode client station, the downlinksubframes occurs periodically at a 2.5 ms offsets, or more generally, attwice the rate of the backward-compatible advanced mode frame structure302. In such a configuration, the sub-subframe boundary within thesubframes 310 and 312 can remain configurable, such as, for example, toadapt to current loading etc.

As such, the legacy frame is divided in such a way that it supports twoadvanced technology DL/UL pairs for each legacy DL/UL pair. As comparedwith the frame structure in FIG. 3 a, the low latency advancedtechnology frame structure in FIG. 3 b provides for a shorter cycle timebetween the downlink and uplink, thereby lowering latency. In order tofurther reduce the latency, the legacy frame can be divided in such away that it supports three or more DL/UL pairs for each legacy DL/ULpair.

Low latency is achieved by reducing the time lag between successiveadvanced mode downlink (or uplink) sub-subframes. For example, note thatin FIG. 3 a a downlink transmission that enters the transmission queuejust after the advanced mode map is generated may remain queued at leastuntil the next downlink subframe. As such a downlink transmission mayremain queued about 5 milliseconds (msec or ms), even when the systemhas ample capacity to service the transmission.

In comparison, note that in FIG. 3 b, an advanced mode downlinktransmission that enters the transmission queue just after the advancedmode map is generated has a much shorter maximum wait time becauseadvanced mode downlink sub-subframes occur every 2.5 msec on average.The average latency can be yet further reduced by increasing the numberof downlink sub-subframes that occur within any legacy subframe. Thesesame principles apply directly to uplink advanced mode transmissions.

FIG. 4 is a simplified timing diagram of time synchronization betweenembodiments of advanced technology frame structures. The upper timingdiagram illustrates the advanced technology frame structure with lowlatency. The lower timing diagram illustrates an example of a legacyframe structure synchronized to the advanced technology frame structure.The legacy frame can be, for example, a frame generated by a neighboringbase station lacking the capability to support advanced technologycommunication. These co-existence techniques can be critical when dualmode base stations operate in close proximity to single mode basestations.

As shown in FIG. 4, the beginning of the low latency, backwardscompatible advanced technology frame 304 transmitted by a first basestation is time synchronized with the beginning of a compatible legacyframe 400 transmitted by a second, neighboring base station.Alternatively, advanced technology frame 304 and the legacy frame 400may be transmitted by a common base station but on different frequencybands/channels. The first base station transmitter and second basestation transmitter neighbor one another when the coverage areacorresponding to each base station is within a localized geographicalregion or when the two transmitters are substantially co-located andoperating in different frequency bands/channels. The legacy framerefrains from having resources allocated during the first advancedtechnology uplink sub-subframe and the second advanced technologydownlink sub-subframe in order to mitigate the deleterious effects ofcollisions between uplink and downlink transmissions.

Transmission or receptions within the various subframes may terminate ator before the end of the corresponding subframe. During periods of heavytraffic, communications may occur throughout an entire subframe. If thesystem is not fully loaded, communications may not occur over someportion of a subframe.

The duration over which communications are conducted within the limitedsubframes 410 and 412 is reduced to a limited downlink sub-subframe 402and a limited uplink sub-subframe 404 respectively. As shown in FIG. 4,the beginning of the subframe 310 and the beginning of the limitedlegacy downlink subframe 410 are synchronized to time A. Thesub-subframe 402 ends at time B, coinciding approximately with thebeginning of the uplink advanced mode sub-subframe 324. Likewise thesub-subframe 322 ends at time B. The end of uplink advanced modesub-subframe 324 coincides with the end of the downlink subframes 310and 410 at time H.

In a similar manner, the downlink advanced mode sub-subframe 332 beginsat the beginning of the uplink subframes 312 and 412, at time H. Thedownlink advanced mode sub-subframe 322 ends at time C. The sub-subframe404 and the sub-subframe 330 are synchronized to begin at time C. Thesub-subframe 404, the subframe 412, the subframe 312 and thesub-subframe 334 terminate at time D or earlier.

In some embodiments, the occurrence of time B and time C isconfigurable, typically as a system wide parameter. The ordering of theuplink legacy sub-subframe 330 and uplink advanced mode sub-subframe 334can be reversed. The time at which the downlink legacy sub-subframe 320ends and the downlink advanced mode sub-subframe 322 begins, indicatedas time J on FIG. 4, can be configurable and may change from frame toframe and from base station to base station. For example, if the time Jis configurable on a frame to frame basis, it may be changedperiodically, such as every second, every frame, based on loading or thelike. Likewise the time at which the uplink legacy sub-subframe 330 endsand the uplink advanced mode sub-subframe 334 begins, indicated as timeI on FIG. 4, can be configurable and may change from frame to frame andfrom base station to base station.

FIG. 5 is a simplified timing diagram of alternative timesynchronization between embodiments of advanced technology framestructures. In the embodiment of FIG. 5, the timing of the advancedtechnology frame is offset from the frame timing for the legacy frame500 by some fixed amount. The limited uplink subframe 510 includes alimited sub-subframe 504 that is synchronized to occur during theadvanced technology uplink sub-subframe 334 within the downlink subframe310. The limited legacy downlink subframe 512 includes a limitedsub-subframe 502 that is synchronized to occur during the downlinkadvanced technology sub-subframe 332 within the uplink subframe 312. Insome systems, the configuration shown in FIG. 5 may be advantageouslyapplied as the ratio of resources dedicated to the advanced modeoperation increases. Note that in typical systems, the uplinksub-subframe 504 corresponds to the frame before the frame that includesthe downlink sub-subframe 502.

Thus, the beginning of the sub-subframe 332 and the beginning of thelegacy downlink sub-subframe 502 are synchronized to begin a time F. Thelegacy downlink transmissions in the sub-subframe 504 are terminated attime G or earlier. Likewise transmission in the sub-subframe 332 areterminated at time G or earlier. In a similar manner, the legacy uplinksub-subframe 504 and the sub-subframe 334 are synchronized to begin atime E. The legacy uplink transmissions in the sub-subframe 504 areterminated at time F or earlier. Likewise, the advanced mode uplinktransmissions in the sub-subframe 334 are terminated at time F orearlier.

FIGS. 6 a-d are simplified timing diagrams of alternative embodiments ofan advanced technology frame structure as seen from different deviceperspectives. FIGS. 6 a-6 d do not specify or otherwise label theadvanced technology sub-subframes as supporting downlink or uplinkcommunications. Although FIGS. 1-5 illustrate specific examples ofadvanced uplink and advanced downlink configurations, the advancedtechnology region is not limited to any particular configuration, andthe advanced technology region can be divided into virtually any numberof uplink and downlink sub-subframes and such advanced sub-subframes mayoccur in any order. For example, as shown in FIG. 2, the advancedtechnology downlink region can occupy substantially all of the advancedtechnology sub-subframe immediately following the legacy downlinksub-subframe. Alternatively, as illustrated in FIG. 3 b, the advancedtechnology sub-subframe can be divided into a downlink/uplink pair,triple etc. Other configurations can be, of course, implemented to betailored to specific communication needs in a system.

Typically, when the advanced mode technology is initially deployed,legacy usage greatly exceeds advance technology usage. As time movesforward, legacy usage decreases and is eventually phased out. Accordingto the embodiments shown in FIGS. 1 b and 2, even after the usage of thelegacy technology is fully phased out, the advanced mode operationcontinues to use one or more elements of the legacy header and, thus,these legacy elements continue to be transmitted even after use of thelegacy system has been phased out.

For example, according to the embodiment shown in FIG. 2, a clientstation operating in advanced technology mode uses both the legacypreamble as well as information embedded in the legacy downlink map andlegacy uplink map. In the embodiment shown in FIG. 1 b, although aclient station operating according to the advanced mode technology doesnot use the legacy header to acquire mapping etc. information, it usesthe legacy header for some elements, such as the preamble. Thus,according to the embodiment shown in FIGS. 1 b and 2, elements of thelegacy header are used in the advanced technology mode operation evenafter legacy operation has been phased out.

FIG. 6 a illustrates an alternative advanced technology frame structurein which the advanced technology frame is decoupled from the legacytechnology frame. The advanced technology enabled base station is ableto support communications with client stations that are configured toreceive either the legacy frames or the advanced technology frames orboth. Since both the legacy and the advanced technology portions in theframes are multiplexed to the air link in a time division manner, theadvanced technology enabled base stations can allocate or process datain resource allocations in each of the sub-subframes to supportcommunications with all client stations.

The backward-compatible advanced technology mode frame structure 600includes a legacy downlink subframe 602. However in contrast tooperations such as shown in FIGS. 1-5, the advanced mode client stationsneed not monitor or any portion of the legacy downlink subframe 602, asclearly illustrated below in FIG. 6 c. The frame structure 600 alsoincludes two advanced mode fields 604 and 610. As shown earlier withrespect to FIG. 3 b, the fields 604 and 610 may include one or moreadvanced technology uplink or downlink sub-subframe (not shown.)

In the embodiment shown in FIG. 6 a, the advanced mode field 604includes a stand-alone advanced mode header 620. In this way, advancedmode operation may be independent of the legacy operation. As such, acustom header tailored for the needs of the advanced mode operation maybe developed and legacy header usage can be eliminated when legacyoperation is phased out.

FIG. 6 b illustrates a legacy client station perspective of an advancedtechnology frame structure embodiment, such as the embodimentillustrated in FIG. 6 a. As illustrated in FIG. 6 b, the legacy clientstation does not communicate over the advanced technology sub-subframes,and likely has no awareness of the advanced technology sub-subframes.From the perspective of the legacy client station, the advancedtechnology sub-subframes appear as regions within which the clientstation is not allocated any resources.

FIG. 6 c illustrates an advanced technology enabled client stationperspective of an advanced technology frame embodiment, such as theembodiment illustrated in FIG. 6 a. As shown in FIG. 6 c, the advancedtechnology enabled client station makes no communications over thelegacy subframes, assuming that the advanced technology enabled clientstation does not support legacy communications. Such operation aspossible because of the inclusion of the stand-alone advanced modeheader 620. In contrast, according to the embodiment shown in FIGS. 1-5,the advanced mode client station monitors a portion of the subframe 602in order to obtain certain information included in the legacy frame.

As described earlier, the time division multiplex operation does notneed to allocate fixed amounts of time to support either the legacycommunications or advanced technology communications. Thus, the amountof resources dedicated to supporting each type of communication maydynamically vary based on the load placed on each type ofcommunications.

There may be few advanced technology enabled client stations at theinitial rollout of the advanced technology system, and thus minimalresources and sub-subframe duration may be allocated to supporting theadvanced technology communications. Over time, more advanced technologyenabled client stations will begin to use the system. At some point intime, virtually no legacy client stations will exist, and the framestructure supports the ability to allocate minimal resources andsub-subframe duration to supporting the legacy communication.

FIG. 6 d illustrates the advanced technology frame at a time in whichsupport for legacy communications has substantially been eliminated. Theentire downlink and uplink subframes may be dedicated to supportingadvanced technology communications. In contrast, in the embodimentsshown in FIGS. 2 and 3 b, some elements of the legacy subframe continueto be used in advanced mode operation even after all legacy devices havebeen phased out of the system.

In some systems, when the advanced technology system is first deployedand the ratio of legacy to advanced mode usage is quite high, it isefficient for advanced mode operation to use certain overheadinformation carried in the legacy mode sub-subframe. By using overheadinformation carried in the legacy mode sub-subframe, the advanced modesub-subframe need not carry such information and can be more fullydedicated to carrying advanced mode data.

However, sometimes the legacy frame overhead is not optimal for use inadvanced mode operation. For example, it may be advantageous to use animproved preamble or a new map format for advanced operation. To theextent that the advanced mode operation relies on elements of the legacysub-subframe, the ability to incorporate differences between legacy andadvanced mode operation is limited. Thus, in some implementations, theembodiments shown in FIGS. 1-5 are advantageous at initial deploymentwhile the embodiment shown in FIG. 6 may have long-term advantages. Assuch, a system may be designed which transforms over time from animplementation consistent with FIGS. 1-5 to an implementation consistentwith FIG. 6.

FIGS. 7 a-c are simplified timing diagrams of embodiments of an advancedtechnology frame structure with legacy compatibility operating in afurther expanded frequency dimension. As previously illustrated, theadvanced technology frame structures can be implemented by a system thatoperates and occupies the same bandwidth as a legacy communicationsystem. However, the frame structure is not limited to maintaining thesame frequency bandwidth in the advanced technology system, as will bedescribed below.

FIG. 7 a illustrates, from the perspective of an advanced technologyenabled base station, an advanced technology frame structure thatsupports legacy communications with additional operating bandwidth ascompared with the legacy system. The advanced technology frame structuremaintains the time division multiplexing of the legacy sub-subframes andthe advanced technology sub-subframes. However, the advanced technologyframe also supports communications in expanded frequency dimensions,incorporating a frequency division multiplexing component. The followingexamples illustrate frequency expansion both above and below thefrequency bands allocated to the legacy communication system, but theadvanced technology frame structure can readily be applied to one sidedfrequency expansion as well.

As shown in the timing diagram of FIG. 7 a, each of the subframeportions has a frequency portion supporting advanced technologycommunications. The additional frequency portion can be, for example,additional subcarriers of an OFDMA symbol. There can be one or morepredetermined guard bands isolating the legacy frequency bands from theappended frequency portions, but these guard bands may be eliminated orotherwise omitted in those subframe portions that support advancedtechnology communications.

As shown in FIG. 7 a, an advanced technology enabled base station canconfigure both the advanced technology portions and the legacy portionsof the frame structure. Although the advanced technology portions notappended to a legacy sub-subframe may be configured to carry eitherdownlink or uplink communications, those advanced technology frequencybands that are appended to the legacy sub-subframes typically areconfigured to support the same communication direction as supported bythe associated legacy sub-subframe. For example, the advanced technologyfrequency bands appended to the downlink sub-subframe will be configuredfor downlink communications, while the advanced technology frequencybands appended to the uplink sub-subframe will be configured for uplinkcommunications.

FIG. 7 b illustrates the wide band advanced technology frame structurefrom the perspective of a legacy client station. The legacy device hasno awareness of the advanced technology regions or is not allocatedresources within any of the advanced technology sub-subframes orfrequency regions from the perspective of the legacy device the advancedtechnology.

FIG. 7 c illustrates the wide band advanced technology frame structurefrom the perspective of a wideband advanced technology enabled clientstation. In the embodiment of FIG. 7 c, the advanced technology clientstation is assumed to not support legacy communications.

From the perspective of the wideband advanced technology enabled clientstation, the frame structure supports advanced technologycommunications, with minor limitations on uplink and downlinktransmissions in the sub-subframe portions that overlap the legacysub-subframes. These limitations diminish as the resources allocated tolegacy devices shrinks.

FIG. 8 is a simplified functional block diagram of a system 800implementing an advanced technology frame structure. The wirelesscommunication system 800 includes a plurality of base stations, 810-1and 810-2, coupled to a network 814, such as a wide area network. Eachbase station, e.g. 810-1, services devices within its respectivecoverage area, e.g., 812-1, sometimes referred to as a cell.

A first base station 810-1 serves a first coverage area 812-1 and asecond base station 810-2 serves a corresponding second coverage area812-2. The base stations 810-1 and 810-2 are depicted as adjacent orotherwise neighboring base stations for the purposes of discussion. Inone embodiment, the base station 810-1 comprises two base stationtransmitters configured to transmit on different frequencychannels/bandwidths.

As an example, the base stations 810-1 and 810-2 serve those deviceswithin the respective coverage areas 812-1 and 812-2. As shown in FIG.8, first and second client stations or client stations 820 a and 820 bare within the first coverage area 812-1 and can be supported by thefirst base station 810-1.

For the purposes of discussion, the first base station 810-1 can supportadvanced technology communications as well as legacy communications. Thesecond base station 810-2 can be limited to supporting legacycommunications. Similarly, assume for the purposes of discussion thatthe first client station 820 a is advanced technology enabled, while thesecond client station 820 b is a legacy device, incapable of advancedtechnology communication.

The first base station 810-1 can support communications with both thefirst and second subscribe stations 820 a and 820 b by implementing anadvanced technology frame structure such as one illustrated in FIGS.1-7. The first base station 810-1 can allocate legacy resources to thesecond client station 820 b in the legacy sub-subframes and can allocateadvanced technology resources to the first client station 820 a in theadvanced technology sub-subframes. As discussed earlier, the advancedtechnology sub-subframes are time division multiplexed with the legacysub-subframes in the duration of a legacy subframe portion.

The advanced technology frame timing implemented by the first basestation 810-1 can be synchronized to the frame timing of the legacysecond base station 810-2, such as exemplified in FIG. 4, to minimizethe collisions that may occur if the advanced uplink sub-subframes occurduring the legacy downlink subframes, or if advanced downlinksub-subframes occur during the legacy uplink subframes.

FIG. 9 is a simplified functional block diagram of an embodiment of abase station 810 implementing an advanced technology frame structure.The base station 810 includes both transmission and receptioncapabilities and is some times referred to as a base stationtransmitter/receiver.

The base station 810 can be, for example, the first base station 810-1shown in the wireless communication system of FIG. 8. The base station810 includes the capabilities to configure and support one or moreadvanced technology sub-subframes in each legacy subframe. The basestation 810 functionality is simplified to include those portions thatoperate as part of advanced technology support. Other portions of thebase station 810 are omitted for the purposes of brevity and clarity.

The base station 810 includes an antenna 902 coupled to an output of atransmitter 960 as well as to an input of a receiver 910. The output ofthe receiver 910 can be coupled to an input of a Uplink MessageProcessor 920 that can be configured, for example, to process uplinkresource allocation requests from legacy and advanced technology clientstations. The uplink message processor 920 can inform a scheduler 970 ofthe requests.

The scheduler 970 can be configured to determine the resources toallocate to legacy communications as well as advanced technologycommunications. The scheduler 970 can be configured to control theduration of the time division multiplexing of the legacy subframes aswell as any frequency multiplexing employed. In one embodiment, thesevalues are dynamically varied, and each base station can be configuredto independently determine them. In another embodiment, the scheduler970 determines the resources to allocate based on one or more settingsreceived from a system controller (not shown, but which may be anelement of the network 814.) These settings may influence the timedivision multiplex timing as well as any frequency multiplexing.

The scheduler 970 can be configured to control a multiplexer 974 that isconfigured to time division multiplex a subframe portion of a legacycommunication system into a legacy sub-subframe and an advancedtechnology sub-subframe based on a control from the scheduler 970.

The scheduler 970 can also control a legacy resource mapper 942 as wellas an advanced resource mapper 944. Each of the legacy resource mapper942 and advanced resource mapper 944 can be configured to selectivelyreceive data from a data source 930 and map it to an appropriatesub-subframe. The scheduler 970 can control or otherwise enable theselection of the data by the active resource mapper.

The legacy resource mapper 942 is configured to allocate legacycommunications to the legacy sub-subframe and the advanced technologyresource mapper 944 is configured to allocate advanced technologycommunications to the advanced technology sub-subframe.

The output of the legacy resource mapper 942 is coupled to a legacydownlink signal processor 952 that configures the legacy downlinksub-subframe using the data mapped by the legacy resource mapper 942.Similarly, the output of the advanced resource mapper 944 is coupled toan advanced downlink signal processor 954 that configures the advancedtechnology downlink sub-subframe using the data mapped by the advanceresource mapper 944.

The outputs of the legacy downlink signal processor 952 and advanceddownlink signal processor 954 are each coupled to respective inputs ofthe multiplexer 974. The active multiplexer path, as determined by thescheduler 970, is coupled to the transmitter 960 for downlinktransmission over antenna 902.

Typically, the various elements shown in FIG. 9 are controlled by aprocessor 972 which is capable of directing the functioning of one ormore of the elements shown in FIG. 9. (Connections Between the VariousElements are not Shown so as not to Complicate the Diagram.) Typicallythe operation of the processor 972 is accomplished with reference to oneor more storage media, such as a memory 974. The functionality of all orportions of one or more of the elements shown can be implemented as oneor more computer readable instructions encoded on one or more storagemedia.

FIG. 10 is a simplified functional block diagram of an embodiment of aclient station 820 supporting-advanced technology frame structure. Theclient station 820 can be, for example, an advanced technology enabledclient station, e.g., 820 a, in the wireless communication system ofFIG. 8.

The client station 820 includes a receiver configured to receive a timedivision multiplexed subframe portion of a legacy communication systemhaving a legacy sub-subframe and an advanced technology sub-subframe.

The client station 820 includes an antenna 1006 through which the uplinkand downlink signals are communicated. The antenna 1006 couples thedownlink signals to a transmit/receive (T/R) switch 1010. The T/R switch1010 operates to couple the downlink signals to the receiver of theclient station 820 during a downlink subframe and operates to coupleuplink signals from the transmitter portion of the client station 120during an uplink subframe.

During the downlink portion or subframe, the T/R switch 1010 couples thedownlink signals to a receive RF front end 1020. The receive RF frontend 1020 can be configured, for example, to amplify, frequency convert adesired baseband frequency, and filter the signal. The baseband signalis coupled to a receive input of a baseband processor 1040.

The receive input of the baseband processor 1040 couples the receivedbaseband signal to an Analog to Digital Converter (ADC) 1052 thatconverts the analog signal to a digital representation. The output ofthe ADC 1052 is typically filtered, such as by filter 1053, the outputof which can be coupled to a transformation module, such as Fast FourierTransform (FFT) engine 1054 that operates to convert the received timedomain samples of an OFDM symbol to a corresponding frequency domainrepresentation. The sample period and integration time of the FFT engine1054 can be configured, for example, based upon the downlink frequencybandwidth, symbol rate, subcarrier spacing, as well as the number ofsubcarriers distributed across the downlink band, or some otherparameter or combination of parameters.

The output of the FFT engine 1054 can be coupled to a channelizer 1056that can be configured to extract the subcarriers from those symbolsthat are allocated to the particular client station 120. The channelizer1056 can be configured, for example, to extract the portion of thelegacy or advanced downlink sub-subframes relevant to the client station120. The output of the channelizer 1056 can be coupled to a destinationmodule 1058. The destination module 1058 represents an internaldestination or output port to which received data may be routed.

The client station 120 also includes a legacy map decoder 1070configured to access a resource map from the legacy sub-subframe anddetermine a resource allocation for legacy technology map and anadvanced technology map decoder 1080 configured to access the advancedtechnology map and determine an advanced technology resource allocationin the advanced technology sub-subframe. The legacy map decoder 1070 andthe advanced technology map decoder 1080 can be coupled to thechannelizer 1056 to control the extraction of the data in the allocateddownlink resources. Similarly, the legacy map decoder 1070 and theadvanced technology map decoder 1080 can be coupled to the uplinkchannelizer 1064 to control the allocation of uplink data to theappropriate allocated uplink resources.

The uplink path is complementary to the downlink signal path. A sourcemodule 1062 of the base band processor 1040, which may represent aninternal data source or an input port, generates or otherwise couplesuplink data to the baseband processor 1040. The source 1062 couples theuplink data to an uplink channelizer 1064 that operates to couple theuplink data to appropriate uplink resources that are allocated tosupport the uplink transmission.

The output of the uplink channelizer 1064 is coupled to an FFT engine1066 that operates to transform the received frequency domainsubcarriers to a corresponding time domain OFDM symbol. The uplink FFTengine 1066 may support the same bandwidth and number of subcarriers assupported by the downlink FFT engine 1054.

The output of the uplink FFT engine 1066 is coupled to a Digital toAnalog Converter (DAC) 1068 that converts the digital signal to ananalog representation. The analog baseband signal is coupled to atransmit front end 1022, where the signal is frequency translated to thedesired frequency in the uplink band. The output of the transmit frontend 1022 is coupled to the T/R switch 1010 that operates to couple theuplink signal to the antenna 1006 during the uplink subframe.

A local oscillator (LO) 1030 is coupled to a switch 1032 ordemultiplexer that selectively couples the LO 1030 to one of the receivefront end 1022 or transmit front end 1022 so as to be synchronized tothe state of the T/R switch 1010.

Typically, the various elements shown in FIG. 10 are controlled by aprocessor 1072 that is capable of directing the functioning of one ormore of the elements shown in FIG. 10. (Connections between the variouselements are not shown so as not to complicate the diagram.) Typicallythe operation of the processor 1072 is accomplished with reference toone or more storage media, such as a memory 1074. The functionality ofall or portions of one or more of the elements can be implemented as oneor more computer readable instructions encoded on one or more storagemedia.

FIG. 11 illustrates an advanced technology frame structure 1100incorporating several aspects discussed above. In particular, the framestructure 1100 includes a legacy downlink sub-subframes 1110 that spansa legacy frequency bandwidth 1112. The frame structure 1100 alsoincludes two advanced mode downlink sub-subframes 1120 a in 1120 b whichoccur at a fixed offset from one another. For example, in FIG. 11, thesub-subframes 1120 occur at 2.5 ms intervals. The advanced mode downlinksub-subframes also include stand-alone headers 1122 which obviate theneed for advanced mode client stations to monitor a portion of thelegacy subframes. In addition, the frame 1100 includes two advanced modedownlink sub-subframe portions 1130 a 1130 b, which occur at the sametime as the legacy downlink sub-subframe 1110 and use a portion of theadvanced mode frequency bandwidth 1124. Likewise the frame 1100 includestwo advanced mode uplinks sub-subframe portions 1132 a and 1132 b whichoccur at the same time as the legacy uplink subframe 1114 and use aportion of the advanced mode frequency bandwidth 1124.

FIG. 12 illustrates a process 1200 for creating an integrated, backwardscompatible advanced technology frame structure. In block 1210, a frameheader is created, such as the frame header 206 of FIG. 2, whichincludes the advanced mode allocations, or the header 120 of FIG. 1 b,which includes a pointer to the advanced technology resource map 124within the advanced mode sub-subframe 118. In block 1230, acorresponding frame is created. A portion of the frame is populated withdata using a first technology format, such as, for example, the legacyformat described herein, and a portion is populated with data using asecond technology form, such as, for example, the advanced mode formatdescribed herein. In block 1240, the resulting frame is transmitted overa wireless network. In one embodiment, blocks 1210, 1220 and 1230 areperformed by the legacy resource mapper 942, the advanced resourcemapper 944, the legacy DL signal processor 952, the advanced DL signalprocessor 954, and the scheduler 970. In one embodiment, block 1240 isperformed by the transmitter 960 and the antenna 902.

FIG. 13 illustrates a process 1300 for receiving an integrated,backwards compatible advanced frame structure at a client station. Inblock 1310, a frame header in a first technology format is received. Inblock 1320, the frame header is parsed to determine the location of analternate technology region. In block 1330, a grant of resources withinthe alternate technology region is granted according to a grant messagereceived within the alternate technology format region. In block 1340,data is transmitted or received in the alternate technology formatwithin the alternate technology region according to the grant. Theprocess 1300 illustrates operation at the client station in a systemusing a frame structure such as the one shown in FIG. 1 b where in theadvanced technology resource map 124 is included within the advancedmode region. A similar process can be used to receive a frame accordingto the format shown in FIG. 2. For example, the client station receivesa resource grant message within the first technology format regiongranting allocations within the alternate technology region. The processshown in FIG. 13 may be implemented, for example, by the client stationof FIG. 10.

FIG. 14 illustrates a process 1400 for creating an integrated, backwardscompatible advanced frame structure for transmission over a wirelesslink. In block 1410, a base station, such as the one shown in FIG. 9,creates a subframe designated, according to a first technology standard,as a downlink portion of a frame. For example the first technologystandard may be IEEE 802.16e. In block 1420, a base station timedivision multiplexes the downlink subframe portion into a sub-subframecompliant with the standard and an advanced technology sub-subframe. Forexample, an uplink, advanced mode sub-subframe is inserted into thedownlink subframe. The alternate technology may be an IEEE 802.16m typeor LTE type technology. Among other structures, the resulting structuremay resemble the frame structure 1100 shown in FIG. 11 and may beimplemented by, for example, a base station implemented in accordancewith FIG. 9. In another example, an advanced mode downlink sub-subframeis inserted into a standard-compliant uplink subframe.

FIG. 15 illustrates a process 1500 for using a system that includes bothadvanced mode enabled base station transmitters and legacy only basestation transmitters. In block 1510, a first base station transmittertransmits a downlink subframe beginning at time A and ending at time B.The downlink subframe includes a downlink legacy technology regionbeginning at time B and a downlink advanced technology region ending atime C. Time C is between time A and time B. In block 1520, aneighboring base station transmitter transmits a limited downlinksubframe starting at time A and ending at or before time C. The limiteddownlink subframe does not include any advanced mode regions. In block1530, a receiver corresponding to the first base station transmitterreceives uplink data in an advanced technology region beginning at timeC and ending at time B. The neighboring base station neither transmitsnor receives between time C and B.

FIG. 16 shows a process 1600 for using a system that includes bothadvanced mode enabled base stations and legacy only base stations. Inblock 1610, a first base station receives a first uplink communicationfrom a client station operating according to a first technology format.The first uplink communication is received between time A and B. Inblock 1620, the first base station receives a second uplinkcommunication from a second client station after time B and before timeC, wherein the second client station operates in accordance with asecond technology format. In block 1630, a neighboring base stationreceives, between the time A and B and between time B and C, a pluralityof uplink communications from a plurality of client stations operatingaccording to the first technology format.

As used herein, the term coupled or connected is used to mean anindirect coupling as well as a direct coupling or connection. Where twoor more blocks, modules, devices, or apparatus are coupled, there may beone or more intervening blocks between the two coupled blocks.

The steps of a method, process, or algorithm described in connectionwith the embodiments disclosed herein may be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. The steps of a method, process, or algorithm maybe embodied in a software module as one or more processor or computerreadable instructions encoded in a storage medium executed by aprocessor, or in a combination of hardware and software. The varioussteps or acts in a method or process may be performed in the ordershown, or may be performed in another order. Additionally, one or moreprocess or method steps may be omitted or one or more process or methodsteps may be added to the methods and processes. An additional step,block, or action may be added in the beginning, end, or interveningexisting elements of the methods and processes.

The above description of the disclosed embodiments is provided to enableany person of ordinary skill in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those of ordinary skill in the art, and the genericprinciples defined herein may be applied to other embodiments withoutdeparting from the scope of the disclosure.

1. A method of providing co-existing base stations comprising:communicating through a first base station transmitter/receiver adownlink subframe, the downlink subframe starting at a first time andending at a second time, wherein the downlink subframe includes adownlink legacy technology sub-subframe, a downlink advanced technologysub-subframe ending at a third time and an uplink advanced technologysub-subframe beginning approximately at the third time and ending on orbefore the second time; and transmitting from a neighboring base stationtransmitter/receiver a limited downlink sub-subframe, starting at thefirst time and ending before or approximately at the third time,including only a legacy downlink technology sub-subframe.
 2. The methodof providing co-existing base stations of claim 1, further comprisingrefraining from transmitting or receiving at the neighboring basestation transmitter/receiver between the third time and the second time.3. The method of providing co-existing base stations of claim 1, whereinthe downlink legacy technology sub-subframe ends at approximately afourth time and the downlink advanced technology sub-subframe begins atapproximately the fourth time, further comprising adjusting theoccurrence of the fourth time on a frame to frame basis.
 4. The methodof providing co-existing base stations of claim 1, further comprising:communicating through the first base station transmitter/receiver anuplink subframe, the uplink subframe beginning at approximately thesecond time and ending at a fifth time, wherein the uplink subframecomprises an second downlink advanced technology sub-subframe beginningat approximately the second time, as well as an uplink legacy technologysub-subframe and a second uplink advanced technology sub-subframe havinga boundary therebetween at a sixth time, wherein the sixth time isbetween the second time and the fifth time; and receiving at theneighboring base station transmitter/receiver a limited uplinksub-subframe beginning at approximately at an end of the second downlinkadvanced technology sub-subframe.
 5. The method of providing co-existingbase stations of claim 4, further comprising adjust the occurrence ofthe sixth time on a frame to frame basis.
 6. A method of providingco-existing base stations comprising: receiving at a first base stationa first uplink communication from a client station operating accordingto a first technology format, wherein the first uplink communication isreceived between a first time and a second time; receiving at the firstbase station a second uplink communication from a second client stationafter the second time and before a third time, wherein the second clientstation operates in accordance with a second technology format; andreceiving at a neighboring base station transmitter/receiver between thefirst time and the second time and between the second time and the thirdtime a plurality of uplink communications from a plurality of clientstations operating according to the first technology format.
 7. A methodof providing co-existing base stations comprising: transmitting from afirst base station transmitter a downlink subframe beginning at a firsttime and ending at a second time, wherein the downlink subframe beginswith a downlink legacy technology sub-subframe and ends with an uplinkadvanced technology sub-subframe that begins at a third time; andreceiving from a neighboring base station a limited uplink subframestarting at the third time and ending at the second time.
 8. The methodof providing co-existing base stations of claim 7, further comprisingtransmitting from the neighboring base station a limited downlinksubframe beginning at approximately the second time.
 9. In a system inwhich a first base station transmitter/receiver communicates using adownlink subframe, the downlink subframe starting at a first time andending at a second time, wherein the downlink subframe includes adownlink legacy technology sub-subframe, a downlink advanced technologysub-subframe ending at a third time and an uplink advanced technologysub-subframe beginning approximately at the third time and ending on orbefore the second time, a method of providing co-existing base stationscomprising: creating at a neighboring base station transmitter/receivera limited downlink sub-subframe, starting at the first time and endingbefore or approximately at the third time, including only a legacydownlink technology sub-subframe; and transmitting the limited downlinksub-subframe.
 10. In a system in which a first base station transmittertransmits a downlink subframe beginning at a first time and ending at asecond time, wherein the downlink subframe begins with a downlink legacytechnology sub-subframe and ends with an uplink advanced technologysub-subframe that begins at a third time, a method of providingco-existing base stations comprising: receiving at a neighboring basestation a limited uplink legacy subframe starting at the third time andending at the second time; and refraining from receiving from the firsttime to the third time.
 11. A method of configuring information in acommunication system, the method comprising: time division multiplexinga subframe portion of a legacy communication system into a legacysub-subframe and an advanced technology sub-subframe.
 12. The method ofclaim 11, wherein time division multiplexing the subframe portioncomprises: time division multiplexing a downlink subframe portion of thelegacy communication system into a legacy downlink sub-subframe and anadvanced technology downlink sub-subframe; and time divisionmultiplexing an uplink subframe portion of the legacy communicationsystem into a legacy uplink sub-subframe and an advanced technologyuplink sub-subframe.
 13. The method of claim 11, wherein time divisionmultiplexing the subframe portion comprises: time division multiplexinga downlink subframe portion of the legacy communication system into alegacy downlink sub-subframe and a first advanced technology downlinksub-subframe and a first advanced technology uplink sub-subframe; andtime division multiplexing an uplink subframe portion of the legacycommunication system into a legacy uplink sub-subframe and a secondadvanced technology downlink sub-subframe and a second advancedtechnology uplink sub-subframe.
 14. The method of claim 13, wherein thesecond advanced technology downlink sub-subframe occurs prior to thelegacy uplink sub-subframe.
 15. The method of claim 13, wherein thelegacy downlink sub-subframe comprises an indication of an allocationwithin the first advanced technology downlink sub-subframe.
 16. Themethod of claim 13, wherein the legacy downlink sub-subframe comprisesan indication of a downlink map within the first advanced technologydownlink sub-subframe.
 17. The method of claim 13, wherein the firstadvanced technology downlink sub-subframe comprises a preamble.
 18. Abase station supporting legacy communications and advanced technologycommunications, the base station comprising: a scheduler configured todetermine an amount of resources to allocate to advanced technologycommunications; a multiplexer configured to time division multiplex asubframe portion of a legacy communication system into a legacysub-subframe and an advanced technology sub-subframe based on a controlfrom the scheduler; a legacy resource mapper configured to allocatelegacy communications to the legacy sub-subframe; and an advancedtechnology resource mapper configured to allocate advanced technologycommunications to the advanced technology sub-subframe.
 19. A clientstation supporting advanced technology communications, the clientstation comprising: a receiver configured to receive a time divisionmultiplexed subframe portion of a legacy communication system having alegacy sub-subframe and an advanced technology sub-subframe; a legacymap decoder configured to access a resource map from the legacysub-subframe and determine a resource allocation for an advancedtechnology map; and an advanced technology map decoder configured toaccess the advanced technology map and determine an advanced technologyresource allocation in the advanced technology sub-subframe.
 20. Amethod of communicating comprising: creating a subframe designated as adownlink portion of a frame according to a first technology format; andinserting into the downlink subframe an uplink sub-subframe according toan alternate technology.
 21. A method of communicating comprising:receiving a frame header in a first technology format; parsing the frameheader to determine an alternate technology format region; receiving aresource grant message within the alternate technology format region;and transmitting or receiving alternate technology formatted data withinthe alternate technology format region according to the grant message.22. A method of communicating comprising: creating a frame header for aframe; indicating within the frame header a portion of the framecomprising an alternate technology region; populating a first region ofthe frame with data in a first technology format and the alternatetechnology region with data in an alternate technology format; andtransmitting the frame.